ENABLE NOVALIDATE behaviour bug

From: Mark Richard <mrichard_at_transurban.com.au>
Date: Tue, 29 Jun 2004 16:09:22 +1000
Message-ID: <OFCFBFB092.9C2573A9-ONCA256EC2.002100B2@transurban.com.au>

Hi List,

I regularly have to change the structure of some fairly large tables (~200m rows). Often we use the opportunity to do a full table rebuild if we want to change other settings (such as index locations) but other times we would prefer to modify the existing table.

I currently have the scenario where I need to add a single CHAR(1) column to a 250m row table and populate it with a constant value (new records may have a different value). The approach I am considering is:

alter table blah add (mycol char(1));
update blah set mycol = 'F'; {perhaps include a parallel hint on this statement}
alter table blah modify mycol not null enable novalidate;

I was hoping to use "enable novalidate" to avoid a verification of all records when I know they will be populated. However I noticed that a describe on the table produces unexpected results. Here is a demo:

SQL> desc blah

 Name                                            Null?    Type
 ----------------------------------------------- --------
--------------------------------
 FIRSTCOL                                                 NUMBER

SQL> alter table blah add (mycol char(1));

Table altered.

Elapsed: 00:00:00.04
SQL> desc blah;

 Name                                            Null?    Type
 ----------------------------------------------- --------
--------------------------------
 FIRSTCOL                                                 NUMBER
 MYCOL                                                    CHAR(1)

SQL> alter table blah modify mycol not null enable novalidate;

Table altered.

Elapsed: 00:00:00.04
SQL> desc blah;

 Name                                            Null?    Type
 ----------------------------------------------- --------
--------------------------------
 FIRSTCOL                                                 NUMBER
 MYCOL                                                    CHAR(1)

SQL> insert into blah (firstcol) values (1); insert into blah (firstcol) values (1)

*
ERROR at line 1:
ORA-01400: cannot insert NULL into ("SPARKY"."BLAH"."MYCOL") SQL> alter table blah modify mycol null;

Table altered.

Elapsed: 00:00:00.04
SQL> alter table blah modify mycol not null;

Table altered.

Elapsed: 00:00:00.06
SQL> desc blah;

 Name                                            Null?    Type
 ----------------------------------------------- --------
--------------------------------
 FIRSTCOL                                                 NUMBER
 MYCOL                                           NOT NULL CHAR(1)

This is happening on Oracle 8.1.7.4 (running on Solaris) and is repeatable. Whenever "enable novalidate" is used the constraint doesn't appear. Trying to insert null data shows the constraint is actually there, just not appearing in describe.

Any ideas? Any workarounds? Fixed in Oracle 9 (although we are bound to 8 due to applications that connect)?

Thanks in advance,

Mark.

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Received on Tue Jun 29 2004 - 01:06:24 CDT